FIG. 1 illustrates a conventional radio frequency (RF) transceiver front-end device that is operable in one of a receiving mode and a transmitting mode, and that includes an antenna 11, first and second impedance matching circuits 13, 14, a transceiver switch 12 coupled among the antenna 11 and the first and second impedance matching circuits 13, 14, first and second transformers 15, 16 coupled respectively to the first and second impedance matching circuits 13, 14, and an RF transceiver chip 17. The RF transceiver chip 17 includes a low noise amplifier (LNA) circuit 171 coupled to the first transformer 15, and a power amplifier circuit 172 coupled to the second transformer 16.
When the conventional RF transceiver front-end device is in the receiving mode, the transceiver switch 12 is switched to form a reception path between the antenna 11 and the first impedance matching circuit 13 such that an external first RF signal (Rfs) received by the antenna 11 can be transmitted to the first impedance matching circuit 13 through the reception path. The first impedance matching circuit 13 generates a first matching signal based on the first RF signal (Rfs), and outputs the first matching signal to the first transformer 15. The first transformer 15 generates a pair of differential first induction signals based on the first matching signal from the first impedance matching circuit 13. The LNA circuit 171 amplifies the differential first induction signals generated by the first transformer 15 to generate a pair of differential amplified signals.
When the conventional RF transceiver front-end device is in the transmitting mode, the transceiver switch 12 is switched to form a transmission path between the antenna 11 and the second impedance matching circuit 14. In this case, the power amplifier circuit 172 receives and amplifies a pair of differential input signals to generate a pair of differential output signals. The second transformer 16 generates a second induction signal based on the differential output signals from the power amplifier circuit 172. The second impedance matching circuit 14 generates, based on the second induction signal from the second transformer 16, a second matching signal that is transmitted to the antenna 11 through the transmission path and that is then radiated by the antenna 11 to serve as a second RF signal (Rfs′).
In such a configuration, ideally, when in the receiving mode, the first impedance matching circuit 13 and the first transformer 15 are used to provide impedance matching between the antenna 11 and the RF transceiver chip 17, and when in the transmitting mode, the second impedance matching circuit 14 and the second transformer 16 are used to provide impedance matching between the RF transceiver chip 17 and the antenna 11, making the first and second impedance matching circuits 13, 14 both essential for the conventional RF transceiver front-end device. However, it is noted that the first and second matching circuits 13, 14 are generally composed of inductors and/or capacitors leading to a relatively larger circuit area and a greater manufacturing cost.